1. Field of the Invention
The present invention relates to a scanning type exposure apparatus and more particularly to a scanning type exposure apparatus capable of performing preferable exposure to a substrate expanded and contracted due to a previous exposure process.
2. Related Background Art
Recently, as display devices such as of personal computers, televisions, etc., liquid crystal display devices have been used widely. In such a liquid crystal display device, transparent thin film electrodes are formed on a glass plate in the photolithography in accordance with a predetermined pattern. For the photolithography, projection exposure apparatuses are used in which an original pattern formed on a mask is exposed on a photoresist layer on a glass substrate. There are various step-and-repeat type or mirror projection type exposure apparatuses.
Generally, in such projection exposure apparatuses, an original pattern is exposed on a glass substrate repeatedly one over another for many layers. As a result, the glass substrate is expanded and contracted due to those exposure processes (heat) thereby to be deformed from the initial state. In the conventional step-and-repeat type exposure apparatuses, only one projection optical system is provided, and the expansion and contraction of a glass plate are corrected (magnification correction) by changing the magnification of the projection optical system and changing the stopped position of a substrate stage at the time of each stepping operation thereby to change distances between adjacent transferred images. Also, in the mirror projection type exposure apparatuses, the magnification in the scanning direction is corrected by sequentially changing the relative position of an original plate and a photosensitive substrate with respect to a projection optical system during scanning exposure while the magnification in the direction perpendicular to the scanning direction is corrected by changing the magnification of the projection optical system.